Encyclopedia > Choanoflagellate

  Article Content

Choanoflagellate

The choanoflagellates are a group of flagellate protozoa. They are considered to be the closest relatives of the animals, and in particular may be the direct ancestors of sponges.

Each choanoflagellate has a single flagellum, surrounded by a ring of hairlike protrusions called microvilli, forming a cylindrical or conical collar (choanos in Greek). The flagellum pulls water through the collar, and small food particles are captured by the microvilli and ingested. It also pushes free-swimming cells along, as in animal sperm, whereas most other flagellates are pulled by their flagella.

Most choanoflagellates are sessile, with a stalk opposite the flagellum. A number of species are colonial, usually taking the form of a cluster of cells on a single stalk. Of special note is Proterospongia[?], which takes the form of a glob of cells, of which the external cells are typical flagellates with collars, but the internal cells are non-motile.

The choanocytes[?] of sponges have the same basic structure as choanoflagellates. Collared cells are occasionally found in a few other animal groups, such as flatworms.



All Wikipedia text is available under the terms of the GNU Free Documentation License

 
  Search Encyclopedia

Search over one million articles, find something about almost anything!
 
 
  
  Featured Article
Great River, New York

... For every 100 females age 18 and over, there are 97.8 males. The median income for a household in the town is $78,399, and the median income for a family is $89,566. ...

 
 
 
This page was created in 73.3 ms